Between 1976 and 1990, 231 patients had excision of para-aortic lymph node masses remaining after chemotherapy for metastatic non-seminomatous germ cell tumours. The overall 5-year survival rate was 80%. Multivariate analysis of survival after surgery was performed and the following were found to be independent prognostic variables: completeness of surgical excision, pathology of excised mass, timing of surgery after chemotherapy (elective versus salvage) and year of treatment (before or after 1984). Para-aortic lymphadenectomy provided both therapeutic benefit and histological information of prognostic value in planning future treatment and follow-up. Size of mass and serum markers at the time of surgery were of no additional prognostic value once completeness of excision and pathology were taken into account. We therefore recommend that all residual masses should be removed soon after completion of chemotherapy.